Pull-on diapers having an elastic member extensible in the diaper width direction disposed between the waist opening portion and leg opening portions are known. For example, JP 9-84826A proposes a pull-on disposable diaper, at least the stomach side of which has a first region defined at not exceeding 20 mm above and below the front end of the absorbent core and a second region defined between the first region and the leg opening portions. Elastic members are spacedly disposed in the first region at a smaller interval than in the second region. The proposal aims at leak prevention without impairing the wearing comfort by making the contact with the wearer's body better in the first region than in the second one while substantially equalizing the planar pressure per given area between the first and the second regions.
A pull-on disposable diaper having elastic members disposed at an interval gradually decreasing toward the leg opening is also known from JP U-6-421A. This configuration allows for a strong constrictive force being applied on the wearer's body part above the hipbone.
However, the above-described diapers are still liable to slide or slip down while worn to damage the appearance. The diaper further slides down with the wearer's movement and the weight of urine absorbed. As a result, the crotch portion of the diaper droops and becomes baggy, which tends to interfere with the wearer's movement. Moreover, the waist opening portion exerts a strong constrictive force which can make diapering difficult.
Conventional common pull-on disposable diapers tend to puff out and become baggy around the wearer's crotch while worn. The expression “become baggy” and the term “baggy” as used herein mean “be puffed out excessively”. Baggy diapers interfere with the leg movement of the wearer. Baggy diapers easily get out of right position with the wearer's movement, which tends to cause a leak. Additionally, bagginess of a diaper makes it difficult to put outer clothing, such as shorts and pants, over the diaper only to provide a droopy appearance.
In order to eliminate bagginess of the crotch portion and to provide improved fit at the crotch portion, it is known as effective to have an absorbent member narrowed in the crotch portion. However, a diaper with such an absorbent member has reduced absorption capacity due to the substantially reduced width of its absorbent member in the crotch portion. The portion where the absorbent member is absent is incapable of absorbing bodily waste such as urine. As a result, leakage from the crotch portion easily occurs. The amount of a superabsorbent polymer to be disposed in the crotch portion could be increased to prevent leakage from the crotch portion. Although this configuration provides a good appearance and fit immediately after putting the diaper on a wearer, the crotch portion of the diaper after urine absorption is excessively puffed out due to the swell of the large amount of the polymer, which spoils the appearance.
Various proposals have been made in contemplation to provide both fit and leak protection in the crotch portion. For example, JP 7-28892B discloses a disposable diaper, in which the absorbent member is divided into three pieces; a first piece narrowed in the crotch portion and a pair of second pieces arranged on each lateral side of the narrowed part of the first piece with a gap from the first piece, the first piece being connected to each second piece by a hydrophilic sheet.
Diapers having the opposing second pieces of the three-divided absorbent member configured to rise have also been proposed. For example, JP 10-5274A discloses a disposable diaper, in which the absorbent member is divided into three pieces, a first piece narrowed in the crotch portion and a pair of second pieces arranged on each lateral side of the narrowed part of the first piece with a gap from the first piece, and a leak-preventive cuff having an elastic member along its free edge is provided on the long side portion of each second piece opposite to the first piece. The second pieces rise on both sides of the first piece away from the outermost sheet together with the respective leak-preventive cuffs.
Japanese Patent 2884355 proposes a disposable diaper having a first absorbent member laid flat in the longitudinally extending middle portion of the diaper and a second absorbent member laid on each lateral side of the first absorbent member with a spacing from at least part of the first absorbent member. An elastic member is disposed on the upper part of each second absorbent member to endow the second absorbent member with capability of gathering and rising.
The diaper design having an absorbent member divided into three sections in the crotch portion as disclosed in JP 7-28892B, JP 10-5274A, and JP 2884355 cited supra has a problem that the position where the side absorbent members rise is prone to unsteadiness while worn. Moreover, the central absorbent member disposed in the laterally middle portion of the diaper tends to have an unstable shape, being pressed inwardly by the risen side absorbent members. Therefore, fit and leakage protection in the crotch portion are hardly secured with this design.
The diaper having a leak-preventive cuff along the side of the rising side absorbent member as disclosed in JP 10-5274A can often allow the cuff to be untucked from the leg opening while worn.